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The Internet Was Wrong: Short Chainstays Suck*

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7/19/2016 10:04 AM

I think you need to consider a bike a whole, not just in terms of individual geometry dimensions. Everything needs to work together.

For example, a 26" full suspension bike with long stays may end up feeling similarly balanced to a 29er hardtail with short stays.

I agree that the shorter-is-better preference misses the big picture. But so does absolutely ruling out bikes with short stays.

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7/19/2016 10:10 AM
Edited Date/Time: 7/19/2016 10:34 AM

D(C) wrote:

I think you need to consider a bike a whole, not just in terms of individual geometry dimensions. Everything needs to work together.

For example, a 26" full suspension bike with long stays may end up feeling similarly balanced to a 29er hardtail with short stays.

I agree that the shorter-is-better preference misses the big picture. But so does absolutely ruling out bikes with short stays.

100%. Which is really what I'm trying to say. A bike needs to be well balanced to ride well.

The funny thing is what turned me onto this idea was in fact 29ers with "longer" (compared to my other bikes) stays. I was cornering better, riding faster and just generally having more fun - feeling more comfortable on the bike. I thought it was the bigger wheels, the head tube angle, the BB - until I rode a 27.5" bike with nearly ***identical*** geo numbers less the stays (and rear travel). Then it all came together when I put both bikes on the scales. Bar height, head tube, reach, stem, sweep etc were all the same. Chainstays were the only noteworthy difference.

So yeah, I never ever would have thought bigger wheels with longer stays would allow me to smash corners harder - but sure enough, in this particular case, it did.

But yeah, I'm not trying to say "make all bikes chainstays super long" - what I am saying is now that bikes have grown in front center, perhaps some bikes rear center needs to grow as well (or maybe just the larger sizes - or bikes intended for racing...)

Yes, I'm talking in circles.

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7/19/2016 10:59 AM

jeff.brines wrote:

The Internet Was Wrong: Short Chainstays Suck*

****Disclaimer - Full on bike geekery below - eyes *may* glaze over while reading***

First, a story. Many years ago the bike world was convinced the shorter the rear end of the bike, the better it would corner. Or rather, the easier it was to change direction.The internet forums were rife with thread after thread looking for a bike with the shortest rear end one could cram into a bike. The first iteration of the Specailized Demo circa 2005 really reflected this trend on the longer travel side of things with 16.9" stays. Coincidentally, me owning this bike correlated to my last season of DH racing. My times sucked, I never felt comfortable, and couldn't figure out why.

Fast forward to today, bikes have grown substantially in overall length but many manufacturers are still spec-ing incredibly short rear ends. As many of you know, I ski 6 months a year. This trend of long bikes and short CSs would be akin to skis getting substantially longer but mount points staying in the same location (same amount of tail). For the skiers out there, one can only imagine how silly it'd be to ski a 195 with a -31CM mount point - in short, it'd be terrifying.

Your top two finishers this weekend were both on bikes with "long" (by today's trail bike standards) chainstays. To add, neither of these riders are super tall and both (likely) riding medium frames.

Richie Rude: SB 6c medium - 17.4" chainstays
Sam Hill: NukeProof Mega (guessing a medium) 17.5" chainstays


First things first, yes, both Sam and Richie have talent that is far beyond what any of us that hang around Vital can comprehend, let alone emulate. Put another way, its the the artist, not the brush, and no amount of bike geekery will turn one of "us" into one of "them".

Still, as bikes have grown in length, I've noted this strange push and pull. On one hand I feel much more comfortable on the bike. (EG, my knees don't hit my handlebar, and I no longer look like a circus bear riding a tiny bike) On the other hand its become increasingly hard to get enough weight on the front tire.

When bikes had wheelbases that were 2-3" shorter than today's standard, it would make sense that a short rear center would offer a fairly balanced ride, especially in the small and medium sizes. However, as bikes have grown in front center, manufacturers have stuck by the internet driven adage that "long chainstays suck". Don't get me wrong, for a number of bikes, short rear centers make sense. But for bikes built for aggressive riders trying to go fast, short rear centers are dream crushing, especially in larger sizes.

From a race results perspective, one needs to go no further than Aaron Gwin's first season on Specialized to see what a shorter rear end can do for one of the fastest guys on the planet (he had a bad season until they lengthened the rear end). Minnaar famously had a few breakout races on the now-legendary (yeah, I said it) XXL V10 (with ghastly long 17.75" stays). Even Sam Hill has lengthened his Nukeproof DH bike's rear end to get more weight on the front tire.

This post is meant as a call out for manufacturers to start recognizing this need for longer rear ends to compliment the longer front end. Simply, longer CS measurements are needed to balance the bike. Ideally, each size would have a different rear center (norco does this - getting longer as the size goes up - though they are still too short) to keep this balance in check, but I realize this can be extremely cost prohibitive.

There are objective ways to "test" for this balance, which I won't go into here. But yes, in an XL size, I'd like to see a "throwback" to 17.5-17.75" stays.

Likely? Probably not. But maybe one or two manufacturers will take note and start offering stuff that really is balanced in the larger sizes. The real irony is longer stays can actually make a bike corner **better**, so long as its all kept in proportion.


Without being too long winded, I leave you with the wisdom of Walter Sobcek...(am I wrong?)



Discuss amongst yourselves.

(PS, Team Robot said this a year ago)

*short chainstays are totally legitimate in kids bikes, short people bikes, XS bikes, dirt jumpers, and "I only ride park - bikes"











Not sure if it would change your rationale but I'd be curious to know if both riders you mentioned are in fact on medium frames. I read somewhere that Troy was riding a large size specialized Enduro at that race. If I had to bet, I would say Rude rides a large...he was bigger than me when he was twelve. I ride a medium devinci dixon and always wanted to try the large. The medium is a fun park bike but a little twitchy and unstable at speed.

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7/19/2016 11:17 AM

Minnaar famously had a few breakout races on the now-legendary (yeah, I said it) XXL V10 (with ghastly long 17.75" stays).

How about 18.22 with the custom link!

Photo

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7/19/2016 11:24 AM

stflood wrote:

Not sure if it would change your rationale but I'd be curious to know if both riders you mentioned are in fact on medium frames. I read somewhere that Troy was riding a large size specialized Enduro at that race. If I had to bet, I would say Rude rides a large...he was bigger than me when he was twelve. I ride a medium devinci dixon and always wanted to try the large. The medium is a fun park bike but a little twitchy and unstable at speed.

I have a few sources indicating Richie was on a medium (like Graves used to be). Both are built like linebackers but aren't overly tall (5 10" or 5 11").

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7/19/2016 11:30 AM

What suprises me is that manufacturers claim their new bike is tweeked for optimum weight balance etc. But CS remains the same for all sizes which simply means the bigger the frame sizes the more weight is put on the back wheel. Where is the balance here? Maybe a fixed CS doesn't affect the weight balance much but still.

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7/19/2016 12:48 PM
Edited Date/Time: 7/19/2016 12:56 PM

T

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7/19/2016 12:48 PM

SJP wrote:

Hi Serge-W:

The OP started out with "The internet was wrong, short chainstays suck". Note the footnote associated with it: "*short chainstays are totally legitimate in kids bikes, short people bikes, XS bikes, dirt jumpers, and "I only ride park - bikes"

You close with something much more reasonable: "your experience is different, be happy with it".

Then OP came back a few minutes ago and moderated his tone, so we're all more relaxed now.

Nevertheless, reading your description, we were talking past each other a little bit. When I said "keep body position the same", I was referring to the following: Imagine two bikes with the same wheelbase, and the same positions of seat, handlebars, and body relative to the wheel contact patches. The only difference between the two bikes is that the BB is 0.6" further forward on one bike than the other (so yes, leg angles are slightly different). If we are discussing the effect of chainstay length in particular, that is the thought-experiment I find most relevant. I think you were imagining keeping body position the same relative to the BB, or something other than the wheel contact patches.

Anyway, the OP comes back and was driving at a point I often make: compared to the range of CS lengths from most major bike makers, variation in peoples' bodies (even for a given bike size) results in bigger weight distribution changes than the full range of commercially-available CS lengths. Similarly, compared to differences in typical trail slope from one person's home trails to the next, the effect of CS length within the range of currently-available bikes is small.

I want my next bike to have shorter chainstays than my current bike, but that is because I want a shorter wheelbase than my current bike. That is a more important effect than chainstay length in particular.



Hey! wow, didn't realize that @jeff.brines comment was considered rather rash. For me it was a bit of an exaggeration, but a funny one that was supposed to help drive home his point. But then again, that's just me, non-native speaker wink

yeah, I guess we were talking slightly past each other. I'm trying to look at single variables, so either CS or front center. In your case, your variable is the BB, aka the body anchor point at constant wheelbase. Fair enough. I would still maintain though, that a shift in BB location alters the weight balance of the bike. After all, isn't that what Minnaar did effectively on the XXL V10? I'm saying effectively, because of course they lengthened the bike altogether. But by first increasing reach, and then CS, and maybe going back and forth a bit, they were basically experimenting with different, relative BB locations.

But yeah, the body measurements must be the foundation to all this. It's astonishing how different the experiences are. And then there is the whole short bike is better movement in the 2000s, cramping Steve Peats and Greg Minnaars onto BMX bikes. Is anybody out there aware of any database regarding variability in human body measures?

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7/19/2016 12:58 PM

D(C) wrote:

I think you need to consider a bike a whole, not just in terms of individual geometry dimensions. Everything needs to work together.

For example, a 26" full suspension bike with long stays may end up feeling similarly balanced to a 29er hardtail with short stays.

I agree that the shorter-is-better preference misses the big picture. But so does absolutely ruling out bikes with short stays.

jeff.brines wrote:

100%. Which is really what I'm trying to say. A bike needs to be well balanced to ride well.

The funny thing is what turned me onto this idea was in fact 29ers with "longer" (compared to my other bikes) stays. I was cornering better, riding faster and just generally having more fun - feeling more comfortable on the bike. I thought it was the bigger wheels, the head tube angle, the BB - until I rode a 27.5" bike with nearly ***identical*** geo numbers less the stays (and rear travel). Then it all came together when I put both bikes on the scales. Bar height, head tube, reach, stem, sweep etc were all the same. Chainstays were the only noteworthy difference.

So yeah, I never ever would have thought bigger wheels with longer stays would allow me to smash corners harder - but sure enough, in this particular case, it did.

But yeah, I'm not trying to say "make all bikes chainstays super long" - what I am saying is now that bikes have grown in front center, perhaps some bikes rear center needs to grow as well (or maybe just the larger sizes - or bikes intended for racing...)

Yes, I'm talking in circles.

So, you're recommending the Smuggler over the Patrol. Been curious on what your thoughts where.

To be fair, last 29' bike I had felt like the concept of changing directions was stupid and a sign of weakness. Needless to say, I don't own that bike anymore.

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7/19/2016 1:10 PM
Edited Date/Time: 7/19/2016 1:10 PM

Whattyabike wrote:

So, you're recommending the Smuggler over the Patrol. Been curious on what your thoughts where.

To be fair, last 29' bike I had felt like the concept of changing directions was stupid and a sign of weakness. Needless to say, I don't own that bike anymore.

That's a tough call. For me, I know what I prefer 90% of the time. However, saying I recommend the Smug over the Patrol isn't totally accurate. If you are tall, trying to race and want an extremely versatile bike yes, I think its the call.

If you are shorter, maybe spend more time in a bike park or on fairly gnarly trails, maybe the Patrol is right.

Too many variables but without a question I'm more balanced, more comfortable and riding faster on the Smuggler than the Patrol.

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7/19/2016 2:05 PM

jeff.brines wrote:

100%. Which is really what I'm trying to say. A bike needs to be well balanced to ride well.

The funny thing is what turned me onto this idea was in fact 29ers with "longer" (compared to my other bikes) stays. I was cornering better, riding faster and just generally having more fun - feeling more comfortable on the bike. I thought it was the bigger wheels, the head tube angle, the BB - until I rode a 27.5" bike with nearly ***identical*** geo numbers less the stays (and rear travel). Then it all came together when I put both bikes on the scales. Bar height, head tube, reach, stem, sweep etc were all the same. Chainstays were the only noteworthy difference.

So yeah, I never ever would have thought bigger wheels with longer stays would allow me to smash corners harder - but sure enough, in this particular case, it did.

But yeah, I'm not trying to say "make all bikes chainstays super long" - what I am saying is now that bikes have grown in front center, perhaps some bikes rear center needs to grow as well (or maybe just the larger sizes - or bikes intended for racing...)

Yes, I'm talking in circles.

Whattyabike wrote:

So, you're recommending the Smuggler over the Patrol. Been curious on what your thoughts where.

To be fair, last 29' bike I had felt like the concept of changing directions was stupid and a sign of weakness. Needless to say, I don't own that bike anymore.

jeff.brines wrote:

That's a tough call. For me, I know what I prefer 90% of the time. However, saying I recommend the Smug over the Patrol isn't totally accurate. If you are tall, trying to race and want an extremely versatile bike yes, I think its the call.

If you are shorter, maybe spend more time in a bike park or on fairly gnarly trails, maybe the Patrol is right.

Too many variables but without a question I'm more balanced, more comfortable and riding faster on the Smuggler than the Patrol.

I'd be curious to see what your thoughts are regarding stem length too. I mean People rocking short CS with sub 50MM stems seems like it would naturally cause every bike to feel like they are on a wheelie machines. I'm thinking we've kinda ran with short stems and short CS for a bit too long and trying to make up the length in the wrong place.

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7/19/2016 2:13 PM

Whattyabike wrote:

I'd be curious to see what your thoughts are regarding stem length too. I mean People rocking short CS with sub 50MM stems seems like it would naturally cause every bike to feel like they are on a wheelie machines. I'm thinking we've kinda ran with short stems and short CS for a bit too long and trying to make up the length in the wrong place.

I've played with a number of stem lengths. To be honest, it depends on your stack height (as your bars go up, your "effective" stem length goes down), reach, where you are riding etc.

I will say, in my experience, going north of 60 really isn't (ever) good. Unless you are andre the giant and running an uncut steerer tube wink

Usually, a stem around the length of the fork's offset is a good place to start (40-50mm)

J

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7/19/2016 4:08 PM
Edited Date/Time: 7/19/2016 4:09 PM

jeff.brines wrote:

I've played with a number of stem lengths. To be honest, it depends on your stack height (as your bars go up, your "effective" stem length goes down), reach, where you are riding etc.

I will say, in my experience, going north of 60 really isn't (ever) good. Unless you are andre the giant and running an uncut steerer tube wink

Usually, a stem around the length of the fork's offset is a good place to start (40-50mm)

J

Had tried nearly exact of this idea last season. Was sicking up out of both ends day and night.

To correct all that, I'd used Fork Offset x 1.190476 to generate a stem length



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7/19/2016 4:32 PM

What's with the controversial title, now that you've corrected the misunderstandings, misled by your original post? "Short chainstays suck" = Short chainstays aren't always better. Longer is better for taller riders, racers, and bikes with longer fronts?

You speak of balance, but balance can be found with short CS too. Compared to a Ripley, 17.4" CS, a Intense Spider 275c has a 16.5" CS and feels far more balanced and centered to me, both size med and me 5' 7". I found myself cornering from behind the saddle on the Ripley, while I'm centered 2-wheel-drifting on the Spider. I wasn't setting KOMs on the Spid, but it definitely was radder. Not too self-conscious about actual speed... the feel of going fast is pretty satisfying, even if it's not proved by the clock.

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7/19/2016 5:13 PM

FYI Rude does ride a medium (source: http://enduro-mtb.com/en/pro-bike-check-comparing-richie-rudes-cody-kelleys-yeti-sb6c/)

Interested to know the OP's views on bikes like the Ibis HD3 and Pivot M6? Both have short stays but also keep the reach sensible which should put the rider centred but between a shorter wheelbase than something like an SB6.

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7/19/2016 6:06 PM

Apples to apples I guess. Comparing a snowboard or ski to a bike in terms if balance is like comparing a bike to a motorcycle. Weight distribution in relation to the rider's mass is pretty different, as is the COG height.

Many people like long chainstays, and I bet the same amount swear by short ones. Count me in the second group. I'd trade stability for maneuverability any day. It all comes to your riding style. I like my bikes to turn over a dime, you might feel at home with a different geo.

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7/19/2016 6:17 PM

Specialized demo 8 and YT Tues .
Both at the top and both short chainstays

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7/19/2016 9:00 PM

i guess this thread only about gravity bike , AM & DH bike? how about other MTB like XC and trail bike? people say short CS is better on pedalling. does it counted as a positive value for a bike?

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7/19/2016 9:37 PM

jeff.brines wrote:

Few thoughts to add but before I do I should apologize for this coffee fueled rant. There were a few things I wasn't overly clear on and others I may have blown out of proportion. Unfortunately, I drank more coffee - so this is just as likely to garner a few eye rolls. Apologies in advance...

First, short chainstays (less than 17) often makes sense for smaller sized bikes. My title (short chainstays suck) wasn't really the point, what the title should have been was "chainstays need to be in proportion to the rest of the bike." In shorter reaches, 16.8-17" stays may make for a really balanced ride, but I can't comment being I ride 18.5-19" reach (XL) bikes.

Second, as much as its a throwback to a time I'd prefer not to revisit, adjustable chainstays could really make sense. Yes, I know, it changes your travel/leverage ratio too, but perhaps there is another way to do this that keeps travel the same (like how they lengthened the V10 without changing travel). Or maybe that's too complicated.

As far as SLP's comments about 0.6" not mattering, ankle position, the human head etc etc I guess all I can say is different strokes for different folks. How tall are you SLP? What size do you ride? I have a hunch you may be on a fairly balanced bike as is. (smaller size than me) Or maybe you are an outliar who likes a 40/60 weight distribution. Or you ride in Virgin Utah at the Rampage site wink

Again, to say I'm like Gwin, Minnaar, Hill etc is laughable at best. But for all three of these riders going to longer rear centers has helped their results immensely. Could they ride shorter rear ends? Absolutely! I'm just saying they certainly seem to be able to do everything better on more well balanced bikes.

With respect to my 27.5" trail bike, I'd like my chainstays to go from 16.9" to 17.7" and I'd like my reach to be shortened just a hair too. (about 1/2").

Will this change the bike? Absolutely. We all agree one or two degrees of headtube angle either way make a big difference, a few mm of fork offset make a big difference, 0.6" of travel can make a big difference - so why would it surprise any of us that a few mms of rear center can also change the bike's handling and weight distribution an incredible amount. In my experience, a little length here or there can make a big difference (that's what she said) as to how the bike feels..

To be clear, I'm not saying I "can't ride a bike with 16.9" stays and long reach". I'm just saying I have to fight the bike a bit more than I'd like when trying to ride fast for extended periods of tim. I don't feel well situated in my normal "neutral" position between the two wheels and the scales seem to objectively explain this. I can certainly find this position, but its an awkward position, one where I lose a fair amount of leverage and handling precision. Hence, this post.

Here is the kicker, some riders might be naturally in a good position and like the feel of short stays. And therein lies the problem. The human body is so different person to person. When we can adjust headtube angle (werks/angelset) stem, fork travel, stack height, bar height, to some extent bottom bracket etc but are completely limited when it comes to CSs it leaves many riders on bikes that don't quiet suit them, which again brings me back to "I want an adjustable rear end" comment...

Maybe a company should consider building a bike built for racing alone. Leave playfulness to other models. I see this in other sports. Skiing, sleds, moto etc. I realize the smaller companies couldn't do it, but the larger ones could do a "gravity special" with longer stays in the larger sizes and maybe higher end stiffer valved suspension.

But yeah, now I'm **really** getting carried away.

Thanks to everyone for indulging me in my rant! Good (bike nerd) stuff!!!



Buy a Norco... solved!

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7/20/2016 3:53 AM

utopiaarch wrote:

i guess this thread only about gravity bike , AM & DH bike? how about other MTB like XC and trail bike? people say short CS is better on pedalling. does it counted as a positive value for a bike?

For XC and Trail-riding in general, a long CS means more grip while climbing. But you can't just throw a longer CS at an XC-bike because it adds leverage and you that needs to be taken into account when on the linkage design. I believe that the claim of shorter CS as a better pedalling platform comes from the fact that it puts your weight on the rear wheel so your pedal strokes don't put you deeper in the travel as easily as it would be if your weight was balanced. In our tests we've found out that longer bikes (long CS and long Reach with slack HA) beat shorter bikes that are considered "great at technical climbs" (because of their short CS), and they do that by a mile. On a longer bike climbing up your weight is at the correct position for the rear wheel to grip and if there are obstacles on the way up, a slacker HA makes it possible for the fork to absorb them and you don't get hung-up on square edges.

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7/20/2016 8:29 AM
Edited Date/Time: 7/20/2016 8:30 AM

stiingya wrote:

Buy a Norco... solved!

I do like Norco's method of changing the rear center for every size. However, I'd like to see more growth to keep everything in proportion as, in my opinion, the change isn't enough to make the difference I'd want to see.

So...here is the point to this half-baked rant. I've raced bikes for awhile in a number of disciplines. And yes, I ski. For both skiing and road bikes, there are a number of objective ways to determine mount point, ski length, shaping, stem length, frame size, seat position etc. For mountain bikes, we're still sort of using the "guess and check" method to determining what works and what doesn't. This makes some sense being the modern mountain bike rider is far more "dynamic" than that of the static (in one position more or less) road racer.

Put another way, if anyone has had a real road bike fit, you can attest to it being more of a science and less of an art. I'd like to bring this level of objectivity to mountain bike fit and geometry to get more riders on the best tool for the job. For a number of manufacturers, it really wouldn't matter as this level of customization is beyond their reach from a dollar and sense perspective. (though I still say growing the rear center slightly in the longer sizes will create a more balanced bike no matter what). That said, if you could better explain to a rider what sort of numbers to look for in a bike, you could steer them toward better buying decisions. As someone who has tested a lot of bikes, I can promise better fit/geometry will always trump better suspension. (as suspension can always be improved)

I've run formulas to try and figure out how much the rear center should grow in proportion to front center. As a number of people in this thread have noted, its different than skiing for the reason that there are two weighted points on the bike (handlbar and pedal). The proportion to how this is weighted is going to differ person to person and largely be determined by style, arm length, proportions etc. which is likely why some tall dudes may love short stays and some hate them (me).

If this bias between pedal/bar can be better quantified based of body proportions, perhaps we could arrive at a better fit system that goes more in line toward each rider getting on the right rig than simply following "internet trends"(low bars rule! short chainstays are the truth! Long bikes are the best! Slack HT angles rule! Stiff suspension is the best! etc)

Again, as I noted elsewhere in this thread, the ultimate would be some sort of group of sensors on the bike that could actively determine weight bias while riding and objectively explain what tweaks to geometry/suspension setup etc are doing to the the overall ability for the rider to stay in control.

I know, making a lot of leaps here. Its the internet. And this is a forum. Isn't this what its (internet forums) are for?

J

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7/21/2016 10:02 AM

Varaxis wrote:

What's with the controversial title, now that you've corrected the misunderstandings, misled by your original post? "Short chainstays suck" = Short chainstays aren't always better. Longer is better for taller riders, racers, and bikes with longer fronts?

You speak of balance, but balance can be found with short CS too. Compared to a Ripley, 17.4" CS, a Intense Spider 275c has a 16.5" CS and feels far more balanced and centered to me, both size med and me 5' 7". I found myself cornering from behind the saddle on the Ripley, while I'm centered 2-wheel-drifting on the Spider. I wasn't setting KOMs on the Spid, but it definitely was radder. Not too self-conscious about actual speed... the feel of going fast is pretty satisfying, even if it's not proved by the clock.

With a revised title of "The internet was wrong: long chainstays don't suck", it would be quite accurate.

With a large helping of different body shapes and muscle densities, there is a lot of room for varying preferences. Add in just how big the differences are between terrain and the speeds people take it, there actually should be quite a decent range in preferred CSL.

Similarly playfulness has a few different meanings, and really depends on how people want to dick around on a bike, as well as the trail. For being able to quickly reposition on low speed technical stuff, and quickly modulate the pitch and yaw of the bike, shorter chainstays do carry advantages, particularly for less brawler-shaped riders. For others, being able to set a shock tune with minimal rebound damping to send hops off bonus lines without giving up stability in chunky stuff and being able to modulate weight balance in big drifty cornersis better, and to those riders a longer chainstay setup is going to be more playful. For riders that like both, it may be a terrain dependent preference.

As far as the weight distribution delta - a move of 0.6" of the bottom bracket on a fixed wheelbase is actually non-trivial. Considering that the axle to axle wheelbase of bikes is usually in the 46" range for a medium sized bike, with a chainstay length around 17", this puts a front center length at 29". Moving to half inch longer chainstays, and taking that out of the front center, it's about a 5% change in center of mass location between the two contact patches.

Also consider that in terms of a properly fitting bike with properly located rider that the pedal axle to ankle location is going to be ideally constant (especially when going downhill), therefore the bottom bracket sets the location of the rider's lower body. When in attack position, the only other contact points are the grips, and consequently moving those forward to achieve proper fit is going to move the rider either farther forward also, or rely on adding some stack to keep the overall pythagorean reach-stack sizing the correct size for the rider (basically rolling the rider back @ the hip to get the same fit happening). Especially when adding inclines, the ramifications for these changes on weight distribution at the contact patches are significant.

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7/21/2016 10:27 AM

I think the chain stay balance issue is just a part of the bigger need to scale bikes proportionately..... There seem to be 2 key areas (1) proportionate chainstays and (2) stack to reach ratio.

As far as I know there isn't a manufacturer who broadly maintains stack to reach ratio across sizes. I know for some very small sizes it's hard not to have an extreme high stack relative to reach but in general it's the L/XL/XXL that have the problem of very low stacks that riser bars can't cure.

That means that there's almost no point in asking a tall dude and medium sized dude to compare thoughts because the tall dude already has his weight forward due to the lower relative stack.

People talk about keeping the weight on the front wheel.... I've never had this problem! I wonder what it's like?

JUST on CS.....
I've had bikes with CS ranging from 415 to 450mm (including one with 15mm of adjustable CS) and I've tried a 455 bike. There is no doubt that balanced CS is important and my hats off to Norco for trying to produce what felt like a balanced bike. The adjustable CS was a real eye opener and I agree it's a great idea for letting a tuner ride a bike to their riding needs and size.

Proprotionate CS aren't just needed for balance and high speed but also for climbing if your tall. A steep post is only part of the solution to this issue. I did a bunch of calculations and the balance angle (when the seat is over the rear axle for arguments sake) varied massively for so called All mountain bikes for large sizes. The range was 10 to 17 degrees and I'm sure I didn't find the lowest!

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7/22/2016 5:53 AM

Some of you guys probably would enjoy playing around with an EBB.

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7/27/2016 7:19 AM
Edited Date/Time: 7/28/2016 1:08 AM

And what do you guys think about chainstay length and body position on a hardtail.
I mean, you ride a unsuspended bike differently, right?
More laid-back, less aggressive?
Would love to hear some thoughts about it.

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8/3/2016 4:23 AM

"Richie Rude: SB 6c medium - 17.4" chainstays
Sam Hill: NukeProof Mega (guessing a medium) 17.5" chainstays"

... I guess this argument is now moot

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8/3/2016 4:36 AM

creg wrote:

"Richie Rude: SB 6c medium - 17.4" chainstays
Sam Hill: NukeProof Mega (guessing a medium) 17.5" chainstays"

... I guess this argument is now moot

You could sum it up as "I want everyone to run the same setup I do in order to feel reassured in my elections!"

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8/3/2016 5:10 AM

Thomsen wrote:

And what do you guys think about chainstay length and body position on a hardtail.
I mean, you ride a unsuspended bike differently, right?
More laid-back, less aggressive?
Would love to hear some thoughts about it.

Not read anything else in the thread, was kind of skimming through to see if anybody mentioned hardtails.

I bought a Kona Explosif with adjustable dropouts earlier this year and despite the fact i dont believe shorter=better, i slammed them to the front (425mm). I ride techy, steep, rough trails and this definitely gave the bike a skittish character, felt very reliant on the forks doing their job and letting the rear end bounce around and hopefully follow suit.

After sliding the dropouts back (445mm) i feel a lot more comfortable descending in terms of position and weight distribution on the bike, also, being a hardtail, increasing CS length gives a little more flex and therefore more small bump compliance.

My opinion is that whether HT or FS, the CS length should be proportional to the reach in order to give a balanced riding position, riding with a higher weight distribution over the either wheel is not as efficient as riding with even weight distribution.

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8/3/2016 6:14 AM

responsiblepirate wrote:

Not read anything else in the thread, was kind of skimming through to see if anybody mentioned hardtails.

I bought a Kona Explosif with adjustable dropouts earlier this year and despite the fact i dont believe shorter=better, i slammed them to the front (425mm). I ride techy, steep, rough trails and this definitely gave the bike a skittish character, felt very reliant on the forks doing their job and letting the rear end bounce around and hopefully follow suit.

After sliding the dropouts back (445mm) i feel a lot more comfortable descending in terms of position and weight distribution on the bike, also, being a hardtail, increasing CS length gives a little more flex and therefore more small bump compliance.

My opinion is that whether HT or FS, the CS length should be proportional to the reach in order to give a balanced riding position, riding with a higher weight distribution over the either wheel is not as efficient as riding with even weight distribution.

That last bit is what I'm getting at. 16.x" stays on a small probably feels great! 17.9" on an XL probably feels pretty semi-truck ish and, well, shit.

I'm not saying we need the longest stays on every bike to go fast, but I am saying when looking at the application and overall bike size, going longer in a number of cases really would help the bike work better under the rider.

Alternatively, everyone can go get two scales and check your weight distribution in your neutral position. Stack, head angle, reach, bar sweep, stem, fork pressure, rear shock pressure, tokens etc all play into this but this is number I'm driving toward equalizing. Regardless of the characteristics short/long stays might bring forth, getting the weight distribution nearly 50/50 (with a trail bike) while keeping stem length close to fork offset, reach numbers around 18.5-19 and head angle between 67-66 (29" application) is what I'm after first and foremost. Wish we could bring back adjustable stays for this very reason...

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8/3/2016 8:06 AM
Edited Date/Time: 8/3/2016 8:07 AM

jeff.brines wrote:

That last bit is what I'm getting at. 16.x" stays on a small probably feels great! 17.9" on an XL probably feels pretty semi-truck ish and, well, shit.

I'm not saying we need the longest stays on every bike to go fast, but I am saying when looking at the application and overall bike size, going longer in a number of cases really would help the bike work better under the rider.

Alternatively, everyone can go get two scales and check your weight distribution in your neutral position. Stack, head angle, reach, bar sweep, stem, fork pressure, rear shock pressure, tokens etc all play into this but this is number I'm driving toward equalizing. Regardless of the characteristics short/long stays might bring forth, getting the weight distribution nearly 50/50 (with a trail bike) while keeping stem length close to fork offset, reach numbers around 18.5-19 and head angle between 67-66 (29" application) is what I'm after first and foremost. Wish we could bring back adjustable stays for this very reason...

exactly, its all about proportion, CS should increase with reach.

How well would a human work if the legs never grew proportionally with torso length?

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